Urea-formaldehyde condensation products



a w- 1 1 1 i 2,101,534.

UREA-FORMALDEHYDE CONDENSATIQN i PBODUCTSIQ M DonaldEdwards Edgar,Phlladelphlarrau. assign- Y M or.to ,l l.fl. v du Pont deNemours &Company,

i .wilmingtonfiDel 'a corporation .of Delaware No Drawing.Application-August i, 1935, i 1 'SerialNo. 34,300 i c c A L l (01.260 3)I Thiswinvention relates io condensation prodsodium acid phosphate(NaHzPO il 511 buffer;

ucts of -urea and :formaldehyde, andi more -'par- The hydrogen ionconcentration of the solution ticularly toan improved procedure forpreparis then adjustedto a pH value of 7.6 by the addiing dimethylolurea in a physicalcondition more "tion of sodium hydroxide solution"using Phenol satisfactory for further use. l n Redas an indicator andcomparing; with standard 5 The'reaction product of urea" and 5 aqueouscolor tubes. The ur'ea is thenflissdlved'in the formaldehyde ordinarilyprecipitates as a white formaldehyde solution thus prepaiedfThe liquiderystalline solidwhich.isreadily'soluble in water. is keptrat atemperatureof b'elo'w 25 1C., and i c The bulk of the aqueous materialis usually repreferably not below 15 C.,by any suitable means 10 movedby filtration and the white crystalline and allowed tostand for at least48 hours or 10 preoipitateis then dried usually at ordinary room untilcomplete precipitation of the reaction prodtemperatures or at elevatedtemperatures under uct has taken place. Precipitation usually begins 3controlled conditions. yThe drying of the crystalafter about '12 hoursstanding. When theprecipiline mass offers .difliculties in that thecrystals tation is complete the crystalline material is recakeyin hardlumps which delays the drying time moved by filtration. The crystallinemass is then 15 considerably, thus making the operation ineftreated withethyl; alcohol to form a slurry and flcientl This caking of the crystalsis probably. again filtered to remove the alcohol; This operadue to thecementing action of the'dissolved portion is preferably carried out twotimes. After tion of the crystals from which the aqueous mathe lasttreatment and removal of as much alcohol terial has not been completelyremoved during as possible by filtration the material may be dried 20-the filtering operation. The material thus proby any convenient meanseither at room temperaduced inhard lumps and cakes presents difiicultureor at a slightly elevated temperature. The ties for further use,requiring grinding and crystalline mass thus prepared dries completelyscreening or sieving, The material thus prepared and thoroughly andresults in a fluffy material is often not thoroughly dry and musthere-dried substantially free from any lumps and caking.

. after grinding and screening. Instead of.aqueous formaldehyde I mayuse h e tio h s a O j the provision Dara-formaldehyde. In this case theurea is dis: of an improved procedure for preparing'the resolved inwaterand the para-formaldehyde added action product of urea and formaldehyde.A furas a solid. i

ther object is the provisionoi an improved pro- In place of the ethylalcohol which is used to 30 cedure for preparing dimethylol urea in aphyslwash the crystalline mass after filtration, methyl,,

cal condition inwhich it will be more satisfactory propyl, butyl orother similar aliphaticalcohols '0 fu th imm d 8-. A further ject is aswell as such materialsas acetone, ethyl ether the provision of. animproved method for the prepof ethylene glycol, methyl ether of ethyleneglycol aration of .dimethylol urea which will obviate the and similarmaterials may housed, the principal 5 ss y of th us f d asti rindinprocedures requirement being that the liquid is miscible with i to placethe material in condition for further use, water,

and which will produce a material'of uniform- If desired the crystallinemass, after the al- .quality and relatively uniform physical condition.oohol treatment, may be treated with a liquid 40 Otherobjects willappear hereinafter. l which is miscible with the alcohol used and which40 The o j ar mpli h d. y rem vin does not react with the product of thereaction as much water from the crystalline precipitate as f rea, andformaldehyde. Among such liquids practical y fil ra ion, breaking theresulting may be, mentioned the aromatic hydrocarbons cake into Smallpieces, treating Wi h a iq i such as benzol, toluol and xylol, andaliphatic miscible with Water but a non-solvent f0! the hydrocarbons aspetroleum ether, gasoline, naph. 45

urea-formaldehyde reaction products, filtering thas and the like. anddrying. i The washing with alcohol may be repeated any The followingexample isillustrative of a pre number of times as may be foundpractical; A

ferred embodiment of the invention: convenient modification for thewashing of the Exampz 1 crystalline mass may comprise centrifuging in a50 Grams basket type centrifuge and after the bulk of the v aqueousmaterial is removed spraying with the i liquid to remove the remainingaqueous material p I i as may adhere to the crystalline mass. Many Totheaqueous formaldehyde,v solutionis added variations in this respectwill be readily apparent 55 to those skilled in the art. While thehydrogen ion concentration given in the example above is noted as 1.6,this may conveniently range between 6 and 9, yielding equallysatisfactory results and without departing from the spirit of theinvention The material produced according to the procedure of theinvention may be advantageously adapted for use as a moldingmaterial, assuch, ccording to methods well known in the art. Further, the materialmay be adapted for use as a film-forming composition for particularpurposes either alone or in combination withv other.

synthetic resins and/or suitable softening agents.

This invention presents as a principal advantage a method for producingthe reaction product of urea and formaldehyde, which can be more readilyand efliciently dried after the removal of the aqueous liquid byfiltration and which does not substantially cake or harden into lumps ondrying. The reaction product of urea and formaldehyde produced inaccordance with the present invention is more stable than materialproduced by present procedures, i. 6. dried directly after filtration.The product made by myimproved method, as compared to theurea-formaldehyde reaction product as conventionally made, is also in amuch more suitable physical condition for further use where it may bedesired to dissolve it or react with other materials withthe urea andformaldehyde in aqueous solution thereby obtaining in caked form acrystalline precipitate of said reaction product in aqueous liquor whichis a non-solvent for the precipitated reaction product, separatingsubstantially all said aqueous liquor from the crystalline cakedprecipitate, breaking the resulting cake into small pieces, then forminga slurry of said precipitate with a water miscible liquid which isselected from the class consisting of acetone and alcohols and which isa non-solvent'for said precipitate, separating said precipitate from thenon-solvent. and completely drying the precipitate thereby obtainingsaid urea-formaldehyde reaction product in a fiufi'y form substantiallyfree from lumps and caked particles.

DONALD EDWARDS EDGAR.

